speaker with multi-impedance

[skyclad]

I just saw a picture of a JBL D130 F with stated impedance of 8 - 16 ohms. I couldn't see by the picture but am guessing is has one positive (black for JBL) terminal for 8 ohms and one for 16. What a great idea! Why don't more speakers have this feature?

sky

[PRR]

I am sure it is not dual-impedance.

If you don't use ALL the copper in the magnet gap, efficiency goes away.

There are dual-4-ohm windings for car subwoofers. These can work fine when both coils are used; either as 2 ohms or as 8 ohms. (In car-sound which is stereo and where amp-channels are cheap, the one cone is often driven with two 4-ohm amps.) This also works because small woofers must be very inefficient. But trying to wind a 8/16 coil pretty much ensures complicated and lossy external re-connections, or far more mass in cone and magnet than you would want.

[FYL]

Standard terminals. JBL used a 6.9 ohms voice-coil and called the D130 a 16-ohm model because it's average Z was closer to 16 than to 8 ohms. The K130 reconed or aftermarket 8-ohm versions are fitted with a 5.6 ohms VC.

[skyclad]

here's the one I was talking about -

[FYL]

Pretty standard. The electrically identical Fender version was rated at 8-ohm.

[jeff]

Standard terminals. JBL used a 6.9 ohms voice-coil and called the D130 a 16-ohm model because it's average Z was closer to 16 than to 8 ohms. The K130 reconed or aftermarket 8-ohm versions are fitted with a 5.6 ohms VC.

Speaking of that I have a 15" JBL 130A marked 16 ohms that measures about 5.8 ohms